Des Moines Register Staff Blogs
http://blogs.desmoinesregister.com/dmr/index.php/2012/01/21/isu-meteorologist-climate-change-small-factor-in-weather/January 21, 2012Elwynn Taylor
Iowa suffered its hottest July since the mid-1950s last year and has received below-average moisture since, but agricultural meteorologist Elwyn Taylor of Iowa State University told the Land Investment Expo Friday that climate change accounts for only about 5 percent of whatever weather patterns emerge at a given time.
Taylor told the group that weather patterns tend to run in cycles as long as two decades, and that Iowa has emerged from a period of relatively mild, stable weather to a pattern of colder winters and perhaps hotter, drier summers similar to what happened in the 1950s and again in the 1970s.
“I don’t discount man-made impacts of climate change,’ Taylor said in respones to a question. “But I would put the impact of climate change on our weather right now at no more than 5 percent.”
A greater impact on Iowa’s weather this spring, Taylor said, would be the continuation of the ocean-cooling, La Nina effect that tends to disrupt normal weather patterns. An extension of the current three-year La Nina pattern, he said, could result in a dry spring for Iowa.
If so, that could be bad news for Iowa farmers who already are dealing with inadequate soil moistures in more than half of the state. Western Iowa is particularly dry, with as much as 90 percent of the northwest quadrant classified as in severe drought and with soil moisture deficiencies of 90 percent, according to the U.S. Department of Agriculture.
The snow this weekend won’t help much. ISU agronomist Roger Elmore said that while snow does perform a useful service in holding down wind erosion during winter, it accounts for very little new moisture to the soil because the ground is frozen.
The general ratio of snow to precipitation is given as one inch of “effective rainfall,” as agronomists like to call it, for each ten inches of snow.
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